Several commercial entities offer pipe fitting size charts on their websites, including PlumbingSupply.com and Engineers Edge. Companies that work with particular materials have charts for those materials only, but a company that offers a range of solutions has a comparative chart for various piping solutions.
A comparative chart for a variety of piping options can also be found on the Better Homes and Gardens website as part of its advice on how to effectively measure up for any plumbing job. The chart, in common with most pipe dimension charts, gives both the inside and outside diameter of each type of pipe as well as its approximate circumference and socket depth.
Pipe fitting charts are necessary because their inner diameter is used for ordering and calculations. This is also known as the nominal size. However, a person measuring a pipe is much more likely to be able to measure the outside diameter, so a conversion tool is required. Additionally, the table allows workers to calculate the correct socket depth for a nominal size of pipe. Sockets need to be considered when calculating the length of pipe required, as they need extra overlap, which varies according to the depth of the socket.